Transformer cooling system



June 1925- 1,539,837

s. Q. HAYES TRANSFORMER. COOLING SYSTEM Filed 411g. 15, 1919 I FlyWITNESSES: INVENTOR ATTORNEY Patented June 2, 1925.

UNITED STATES 1,539,837 PATENT OFFICE.

STEPHEN HAYES, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSEELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA,

TRANSFORMER coonmc SYSTEM.

Application filed August 15, 1919. Serial N'o. 317,669.

To all whom it may comem:

Be it known that I, STEPHEN Q. HAYEs, a citizenof the United States, anda resident of Pittsburgh, in the-county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in TransformerCooling Systems, ofwhichfthe following is a specification.

My invention relates to transformercooling systems, particularly asapplied to trans formers of the oil-insulated, water-cooled type, and ithas for its object to provide a system of the character described bywhich the insulating fluid may be effectively cooled by the immersiontherein of a .coilthrough which a cooling medium is passed, without thepossibility of the fluid passing through the cooling coil leaking outinto the insulating fluid upon the development of a leak in the coil,and thereby impairing the efficiency of the insulating qualities of theformer mentioned fluid.

In the accompanying drawing, Figure 1 is an elevational sectional viewof an oilinsulated, water-cooled transformer embodying, my invention;Fig. 2 is an elevational View of transformer and cooling system, inwhich the circulation of the cooling fluid through the cooling, coilsthereof is purely siphonal; and Fig. 3 is an elevational sectional viewillustrating the manner in which my invention may be installed in waterpower generating stations. 3

Some difiiculty has been experienced heretofore in the operation oftransformers as above described, on account of the tendency for whatevercooling medium is passed through the immersedcoil to leak outwardly andinto the insulating fluid "upon the development of a fault in the coilwall. Any such admixture results in a decided impairment of theefiiciency of the insulating fluid. In order to avoid this possibility,in some instances where it was imperative that the insulating fluid bemaintained with a high factor of safety,it'has been necessary toestablish cooling systems in which the 1nsu-' lating fluid is drawn fromthe transformer tank and passed through a 'coohng means which isexterior to the tank itselfwfThis method is, of course, quite expensiveand reinsure that, upon the development of a fault, ,m thef coil wall,the insulating fluid will ,pass into the inside of thecoil and there mixwith the cooling medium and be drawn off. Inasmuch as none of thecooling me dium, which is usually water becomes mixed with theinsulating fluid, which is usually oil, no harmful results will occur ifsome small fault develops whereby the wall of the coil is punctured.Having established the above method as one in which the difficultiesheretofore attendant upon the use of.

cooling coils in oil-insulated, water-cooled transformers are obvlated,I, furthermore,

find that the use of a cooling system of the character described isespecially beneficial in those power plants which are located ad-]acenttoa dam or other stream obstruction and in which the power isfurnished by the difference in head of two bodies of water.

As will hereinafter appear, I employ either a siphoning arrangement or anegative pressure pump to circulate the cooling medium through the coil,and find that an arrangement of this character maintains the requireddifference in pressure between the cooling medium and the insulatingfluid with'which the cooling coil is in contact. Another advantage of myproposed system results when the siphonal method is used inasmuch asafter the siphonal circulation is once established, no pumping means arenecessary to maintain the circulation, all of the work being done by theatmospheric pressure and by the difference in level of the outlet andinlet to the cooling coil. It should be mentioned, however, that in allcases, it is necessary that both the body of fluid from which the inletis supplied as well as that to which the outlet is connected must beentirely below the level of the coil through which it is desired thatthe cooling medium circulate.

Referring now more particularly to the drawing, an oil-insulated,water-cooled transformer comprising a casing 1, and a core 2,embraced-by co1ls3, is shown. The

casing 1 is substantially filled withan insulating fluid which surroundsthe coil and core and tends to maintain the temperature of the samewithin reasonable limits.v As the insulating fluid becomes heated, it.rises to the top, and in so doing, flows into contact with a coolingcoil 4, through which is passed any suitable cooling medium which, forpurposes of illustration only, I have designated, in this description,as water. A storage tank 5 is kept constantly filled with cooling fluidand is connected to the inlet of the coil 4 through a connecting pipe 6and to the outlet of the coil 4 by a pipe 7, pumping means 8 beinginterposed between the outlet of the coil and the connection thereofto.the storage tank 5, whereby the coolingfluid is sucked through thecoil and negative pressure maintained therein as long as the pumpfunctions in the normal manner.

Referring now to Fig. 2, I have shown somewhat diagrammatically atransformer casing and the cooling coil 4 immersed therein. In order tomaintain a negative pressure within the coil et by the use of puresiphonal circulation, it is necessary that the coil itself be whollyabove the level of both the supply fluid and the discharged body offluid. I have indicated the tank of cooling fluid supply as 5 and thedischarged body of fluid as 5*. In this structure, the circulation ofthe cooling fluid through the coils is effected by siphonic action aloneand the pump only functions to return the cooling fluid from the lowerlevel to the higher level. By this construction, the cooling fluid isnot only circulated at a constant pressure through the cooling coils buteconomy in the use of cooling fluid is effected.

It will be observed, therefore, that a cooling system constructed inaccordance with my invention in which the pressure of the cooling fluidflowing through the cooling coil is less than the pressure of theinsulating fluid, results in decidedly economical operation, since allthat is necessary is an adjacent body of water above which thetransformer tank may be placed.

Transformers embodying cooling systems of the character above describedare particularly adapted for employment in water power generatingstations, as may be understood from a consideration of Fig. 3 in which apower house 9 is represented, in elevational sectional view, asporitioned adjacent to the down-stream wall of adam 10, the latterrestraining a body of fluid 11. ater-driven generating machines 12 areshown as supplied with power through a penstock' 13, the .waste waterpassing oil? in a tail-race 14. Transformers of the oilinsulated,water-cooled type, are shown as positioned on an upper floor of thegenerating station 9 in such manner that the cooling coils therein aresubstantially above the body of the fluid 11. It will be observed thatthe pipe 6 constitutes an inlet connection to the coil from the body ofthe fluid 11, while the outlet connection 7 is joined to the tail-race.By this particular location of, and connection of the transformers in, awater side generating station, I am able, after an initialestablishment, to maintain a siphonal flow of cooling fluid through thetransformers, and it will be evident, to those versed in coolingproblems, after a consideration of my improved cooling system, that itis decidedly economical, inasmuch as I no further power is requiredafter the initial siphonal establishment and, moreover, since therequired negative pressure is maintained within the cooling coil.

lVhile I have shown but one embodiment of my invention, it is obviousthat many modifications therein may occur to those skilled in the art,and I desire, therefore,

that my invention be broadly interpreted and that it be limited only bythe showing of the prior art or by the scope of the. appended claims,

I claim as my invention:

1. In a transformer, a core and inductively related coils, an insulatingfluid sur rounding said coils, and a cooling coil in contact with saidinsulating fluid through which a cooling fluid may flow, pressuregoverning means comprising means for initiating a siphonal flow of saidcooling fluid through said coil, and means for thereafter maintainingthe flow without power consumption.

2. In a transformer, a core and inductively related coils, an insulatingfluid surrounding said coils, and a cooling coil in contact with saidinsulating fluid through which a cooling fluid may flow, and pressuregoverning means comprising means for initiating a siphonal flow of saidcooling fluid through said coil, and means for thereafter maintainingthe flow without power consumption, and for further maintaining thecooling fluid at a lower pressure than the pressure of the insulatingfluid whereby the former fluid is prevented from passing into the latterfluid upon the development of a fault in the cooling coil.

3. In a transformer, a core and inductively related coils, an insulatingfluid surrounding said coils, and a cooling coil in contact with saidinsulating fluid through which a cooling fluid may flow, and connectionsfrom the inlet and outlet of the cooling coil to points of differentpressure in a body of'cooling fluid, both of said points being below thecooling coil, whereby a siphonal flow may be established through saidcoil.

4. In a transformer, a core and inductively related coils, an insulatingfluid surrounding said coils, and a cooling coil in contact with saidinsulating fluid through which a cooling fluid may flow, and meanscooling coil immersed in insulatin for initiating a siphonal flow of thecooling fluid, said flow being thereafter maintaine wholly by theatmospheric pressure.

5. In a transformer cooling system, the combination with a transformerhaving a fluid of means'for connecting the inlet an outlet of said coilto points 1n a body of cooling fluid, said connecting points being belowthe July 1919.

level ofsaid coil and means for initially 1 establishing a siphonal flowof the ,iluid in said body through said coil, the slphonal flow beingthereafter maintained by atmos' pheric pressure.

In testimony whereof; I have hereunto subscribed my name this eleyenthday of STEPHENIQ, HAYES.

